Applications growing for mid-IR lasers

MOUNTAIN VIEW, Calif. – New military and sensing applications are expected to drive
the mid-IR laser market in the next few years. These new segments will grow approximately
30 percent per year, compounded annually through 2014, according to a report titled
Mid-Infrared Lasers 2010 from Strategies Unlimited.

The report, published in September 2010, examines the spectrum
region from ~1.8 to ~15 μm.

“What is new is the use of new types of lasers for military
applications, followed by a wide array of sensing applications, from industrial
process controls and environmental monitors to hazardous chemical detection and
new medical diagnostics,” said Dr. Tom Hausken, director of photonics and
compound semiconductors at Strategies Unlimited.

“The most obvious new [technological] development is in
compactness and robustness,” he added, noting that these more compact products
enable more mobile platforms and installation into industrial processes. Semiconductor
lasers, optically pumped semiconductor lasers and optical parametric oscillators
(OPOs) are now more compact and robust. The new technology is much improved over
gas lasers, lamp-pumped solid-state lasers and OPOs designed for scientific purposes,
he said.

Currently, in the mid-IR range, CO2 and solid-state lasers dominate
in materials processing and medical treatment applications, respectively. “The
challenge is to get the cost of the new technologies to the level suitable to the
target application, which is often near the level of an existing, very inexpensive
technology,” Hausken said. “Here the semiconductor laser technologies
have the most promise, but you cannot assume that they can scale easily or quickly
to high volume and low cost. And, anyway, they aren’t the best fit for every
application.”

Imagine a Breathalyzer that can determine whether you have or
don’t have a certain medical condition, Hausken said.

“Knowing this at the time of a doctor or hospital visit
might save a costly and time-consuming test or an expensive treatment,” he
said. “The list of these potential solutions is long.”

“Likewise, imagine that you can place small sensors all
over an industrial plant, or a city, and monitor for environmental hazards or different
types of CO2 emissions. These are just the more dramatic applications. There are
many more.”

In the military segment, mid-IR lasers are used as countermeasures
against heat-seeking missiles. The more advanced missiles are wise to last-generation
countermeasures, so the countermeasures must become smarter than the missiles, Hausken
said.

Various lighting related to thermal vision is another major application
category, he noted, adding that one application is simply to introduce illumination
to create shadows and contrast. But there are also beacons and other applications,
including mid-IR communication links and lidar.

He predicts that many new mid-IR laser technologies will emerge
in the next few years – among them, quantum cascade lasers, which offer a
new approach in certain parts of the mid-IR spectrum. Other semiconductor lasers,
interband cascade lasers and gallium antimonide diode lasers, which mostly cover
different parts of the spectrum, also have different features, he said. OPOs and
amplifiers continue to improve, and there are also advances in solid-state and fiber
lasers for specific parts of the spectrum.

“We agree with Hausken’s overall [market] growth assessment,
and, in fact, it may be more bullish,” said Michael Radunsky, product marketing
manager for Daylight Solutions in San Diego. “We are focused on quantum cascade
and interband cascade lasers and the diode side of the market, but here we have
seen tremendous growth in orders and interest. Further, the types of customers have
grown from scientists and those on the cutting edge to established companies not
populated by laser physicists who now accept the technology as a viable solution
to their sensing needs.”

The report from Strategies Unlimited includes a model for scaling
the wafer-based semiconductor laser products to larger volumes and lower prices.

“There is a need for lower-priced sensor products, which,
for mid-IR lasers, means lower-priced lasers, and many point to semiconductor lasers
as a good platform to do that,” Hausken said. “That generally makes
sense, since the same model has worked for other semiconductor laser products, even
in moderate volumes. In high volumes, it can be extremely advantageous.

“Where one has to be careful is to assume that, since a
product is based on semiconductors, it necessarily can migrate quickly and easily
to high volumes and low prices. First, it may be hard just to scale the technology.
For example, uniformity on larger wafers can be very difficult to achieve. Second,
there is a chicken-and-egg problem that has to be overcome. It happens incrementally,
not in one giant step.

“Finally, large volumes are only great if the prices are
high enough to make a decent margin. If not, it can be more profitable to scale
the company to a smaller volume. If they can be achieved, however, the high volume
opportunities are very exciting. New sensors could be used in medicine and for environmental
monitoring at low cost.”

Recent innovations could help the mid-IR laser market; for example,
quartz-enhanced photoacoustic spectroscopy is an inexpensive way to detect mid-IR
radiation. “Part of the problem is that the detectors can be quite expensive,
especially if they need to be cooled,” Hausken said. “This spectroscopy
can sometimes sidestep that.

This integrated mid-IR laser system
was developed by Fibertek Inc. and Northrop Grumman Defense Systems Div. as an enhancement
to the mid-IR source in the AN/AAQ-24(V) Nemesis directional IR countermeasures
self-projection suite used in fixed and rotary wing aircraft against heat-seeking
missiles. Courtesy of Fibertek and Northrop Grumman.
“The same goes for the uncooled focal plane arrays for imaging.
Since the mid-IR range spans thermal emission, the detector noise declines if you
cool it. This is especially important when the signal is low, or the pixel size
is small. In recent years, the quality and price of uncooled focal plane arrays
has improved. This makes thermal imaging more affordable, which means that various
illumination products are more attractive, too.”

An important market trend is vertical consolidation – customers
buying their suppliers, Hausken said. The vertically integrated companies prefer
to keep the technology in-house – sometimes also selling it outside and sometimes
not – because it sets them apart. Given that landscape, some of the new mid-IR
laser companies will be nice targets for such suitors, he said.

Mid-IR laser technololgy is helping vertically integrated companies
differentiate themselves from competitors in segments such as solid-state lasers
in medical systems, OPOs for military systems and in mid-IR semiconductor lasers
in sensing systems, he added.

Among the challenges faced by mid-IR suppliers are components
that have a hefty price tag because of requirements for exotic materials and coatings,
cryogenic cooling and low manufacturing volumes, according to the report.

The types of technologies that compete with mid-IR lasers depend
on the application, Hausken said. In materials processing, there is competition
mainly from 1-µm solid-state and fiber lasers, and in military illumination, from
the near-IR imaging and illumination technologies. In sensing, there are competing
near-IR lasers in Raman spectroscopy, and lamps and glow bars in Fourier transform
IR.

“There are many competitive technologies, and many are inexpensive,
so it is a great challenge for mid-IR laser suppliers to identify those applications
where they have an advantage, even if the price is higher.”